1. Field of the Invention
The present invention relates to a fuel filler cap for closing the filler port of an automobile.
2. Description of the Related Art
The fuel filler cap is desired to exhibit a stable gastightness when it is closed. Particularly, the fuel filler cap is required not to release its closed state accidentally even where either a direct external force or an external force resulting from a deformation of a car body applied. In the prior art, therefore, there has been proposed the fuel filler caps, which includes an inner cap to be fitted in the filler port and an outer cap to cover the filler port and to thereby perform a turning operation of the fuel filler cap. In these fuel filler caps including the inner cap and the outer cap, it is adopted construction to secure gastightness in that the outer cap is released from the inner cap while leaving the inner cap in its closed state in the filler port where the external force applied thereto.
For example, the fuel filler caps disclosed in JP-B-58-007538, JP-B-05-085425 and Japanese Patent No. 2,510,168 have adopted the aforementioned releasing construction under concern of the case in that the external force is applied upwardly to force the outer cap open by an imperfection based on the operator's handling and by a deformation of the car body generated.
On the contrary, the fuel filler caps disclosed in JP-A-63-020218, Japanese Patent No. 3,075,255 and JP-A-2003-104418 have adopted the aforementioned releasing construction under concern of the cases in that the external force is applied to the fuel filler cap in a transverse or upward direction. On the other hand, the fuel filler caps disclosed in JP-A-2003-104418 and JP-A-2003-160160 have adopted the construction, in which an outer circumference pipe having an outer cap protecting function is released from the outer cap to prevent the inner cap pushed into the filler port when the external force is applied downward to the fuel filler cap.
In this respect, the fuel filler caps disclosed in JP-A-63-020218 and Japanese Patent No. 3,075,255 has a structure, in which the outer cap is released when a part of supporting the outer cap to the inner cap is partially broken. This makes it impossible to mount the released outer cap again on the inner cap. Thus, the entire fuel filler cap has to be replaced once the outer cap is released. Moreover, the fuel filler caps disclosed in JP-A-2003-104418 and JP-A-2003-160160 require a large member, e.g., a side wall defined in the references, that can resist against the external force, as its element. As a result, problems arise to increase the number of members and/or to make a size of the fuel filler cap larger.
Thus, the inventors have made investigations to develop a fuel filler cap having a construction, firstly, in that the outer cap is released from the inner cap where an external force that damages the gastightness of the cap is applied from any directions and, secondly, a construction in that the released outer cap, or the released parts can be reused.